In an emailed statement, the Arizona Department of Corrections said the fight happened in a medium-security yard at the Red Rock Correctional Facility in Eloy, about 60 miles south of the Valley

Officials said the 928-inmate unit will remain on lockdown while the brawl is investigated.

About 80 inmates were involved in the fight. The unit was secured by staff.

Arizona Department of Corrections spokesman Andrew Wilder said officers used pepper spray and verbal commands to break up the fight.

Two of the inmates hospitalized returned to the unit on Wednesday night. The other two were still receiving treatment.

None of the injuries were life-threatening.

The Red Rock Correctional Facility opened in 2006. It is operated by CoreCivic — formerly known as the Corrections Corporation of America — a private prison management company. It is the largest private prison operator in the United States. It runs prisons, jails, detention centers and halfway houses in 20 states.

Earlier this week, the Mesa City Council awarded a contract to CoreCivic to privatize its jail for low-level offenders. People arrested on misdemeanor charges in that city will be housed at the company’s facility in Florence.

City officials said the move will save the city $2 million next year and improve efficiency in transfers and bookings.

People arrested on felony charges in Mesa will continue to be housed in county jails, where the daily housing rate increased from $73 in 2008 to $101 in 2017.